What does the PowerShell script do?

The PowerShell script creates a new user account which has the Password Administrator role in your Office 365 tenancy. This is the lowest level administrative role in Office 365, and is known as the Helpdesk Administrator role in Exchange Online, Microsoft Graph, Azure AD Graph and Azure PowerShell.

The PowerShell script also updates your Azure AD schema to support the use of Custom Attributes in Exclaimer Cloud Signatures for Office 365. It provides the new account with all required permissions to read your users' Custom Attributes from Exchange Online, for use in Exclaimer Cloud Signatures for Office 365.